1. Field of the Invention
This invention relates to valve adjustment apparatus for use in removing a valve adjustment disc from a valve lifter in a valve mechanism of an engine cylinder head.
2. Description of the Prior Art
The job of adjusting the valves of an automobile engine can be time-consuming and costly to the automobile owner. On certain types of engines the job is tedious because of the lack of available tools to aid the mechanic in adjusting the valves in a reasonable amount of time. For example, certain overhead cam engines manufactured by Volkswagen and Audi and other similar engines manufactured in Japan for Crysler have mechanical valve lifters above the valves. The valve lifters carry shims or "valve adjustment discs" of selected thickness for use in making the correct valve adjustment for each valve. The valve lifters in these engines are cup-shaped and the interior of the cup faces downward and fits over the valve. A separate shim is seated in a recess in the top of each valve lifter. The lobes of the camshaft contact the top surfaces of the shims during operation of the engine.
To make a valve adjustment, the mechanic uses a feeler gauge to measure the clearance between the shim and the cam lobe; and if adjustment is required, the shim is removed from the valve lifter and another shim of different thickness is inserted in the lifter to provide the correct clearance adjustment.
Valve adjustments in these engines are most commonly done by using a tool for compressing the valve lifter against the bias of the valve spring to move the valve lifter down relative to the shim. The shim can then be removed. The downward force of the tool against the valve lifter is maintained by forcing the tool against the side of the camshaft, using the cam shaft as a fulcrum to apply the downward pressure for compressing the valve against the valve spring. Such use of the camshaft body as a pressure point for applying sufficient force to compress the valve lifter could damage the camshaft. The valve springs are very stiff and require a substantial amount of force for the mechanic to hold the valve lifter down with one hand while using the other hand to remove the shim from the valve lifter. It is not easy to remove the shim from the lifter in this way because the shim is tightly seated in the valve lifter even when the valve lifter is compressed.
The present invention provides apparatus for removing the shims from the valve lifters, so that the valve lifters can be compressed against the valve springs and held in a compressed position without contacting the camshaft, or any other critical moving part of the automobile engine. The apparatus of this invention facilitates quick and easy removal of all shims from the valve lifters, since the mechanic has both hands free to remove the shims. This can provide a substantial reduction in the amount of time required to perform a valve adjustment.